Sims can’t become soulmates

I also have two Sims at max friendship and romance. They are married and profile shows them as Lovers, Best Friends, and Spouse.  No Soulmate.  I too have tried reducing both their friendship and romance bars, allowing the game to run for 5ish minutes and then begin rebuilding their relationship and have since given up. I have other couples that had no issue becoming soul mates. Only happening with this one. I do not use Mods and the only custom content I have is jewelry. 

My sims have maxed their relationship and friendship bars, are married, are best friends, and still cannot become soulmates (which is needed to complete the soulmates aspiration). I don’t use cheats or mods because I like collecting achievements so there is literally nothing I can do at this point. Tried googling a bunch of stuff to see if there’s a workaround, and apparently this bug is almost 6 years old now.

I am having this issue as well. Fully maxed friendship and romance bars, they are married, best friends, have the close relationship dynamic, but are stuck at only lovers. Neither sim has any other best friends or romantic relationships. I've tried moving each of them separately out of the household and back in, cheating their friendship and romance levels down and then back up, gold star dates and spamming friendly and romantic interactions... I'm playing on xbox so no mods or cc.